1. Field of the Invention
The present invention generally relates to a safety system and technique for protecting against the inadvertent activation of an optical system function and more specifically, to a safety system and technique for deactivation of a system function and warning a user of a multi-aperture optical system that the system function is not ready for activation.
2. Description of Prior Art
Many optical systems become enhanced through the use of more than one aperture. A well known optical system that uses dual apertures is the modern 35 millimeter autofocus camera. These types of cameras utilize a simplified infrared (IR) rangefinder within an auto-focus adjusting device of the camera thereby providing considerable enhancement over prior art fixed-focus cameras. As the shutter button is depressed the auto-focus adjusting device emits an infrared beam from a separate rangefinder window to the target shown within the optical (viewfinder) window. The reflected return infrared beam is detected and the resultant range determined so that the visible optics is correctly focused when the shutter button is completely depressed.
Optical systems that utilize the dual-spectral region detector approach are enhanced in their operation, but are also characterized with a severe drawback. System performance is severely decreased or nonexistent when the infrared optical window is inadvertently blocked. An out of focus picture results when the infrared optical window is blocked (such as inadvertently with a finger).
While the prior art has reported using a dual aperture systems and techniques, none have established a basis for a specific apparatus that is dedicated to the task of resolving the particular problem at hand. What is needed in this instance is a safety system and technique for deactivation of a system function and warning a user of a multi-aperture optical system that the system function is not ready for activation.